how can I take 3 string arrays(contains files) into a single array

Question

1.00/5 (1 vote)

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string[] filesHD = Directory.GetFiles(dirPath, filepattern1);
string[] filesDT = Directory.GetFiles(dirPath, filepattern2);
string[] filesTD = Directory.GetFiles(dirPath, filepattern3);

Here filesHD[] Array contains 2 files. filesDT[] contains 2 files and filesTD[] also contains 2 files. I want to create a single string Array which will contain all the 6 files of filesHD,filesDT,filesTD.

string[]Allfiles=new string [filesHD+filesDT+filesTD].

Please help me to do this.

Posted 16-Jan-14 6:00am

DEbopm

Updated 16-Jan-14 6:22am

Sergey Alexandrovich Kryukov

v2

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Sergey Alexandrovich Kryukov 16-Jan-14 12:23pm

What have you tried so far?
—SA

DEbopm 16-Jan-14 12:27pm

i tried like this ..
string[]Allfiles=new string [filesHD.length+filesDT.length+filesTD.length].

Sergey Alexandrovich Kryukov 16-Jan-14 12:31pm

Isn't it obvious that it does not work? Who told you that the operation + is defined for arrays? Array objects are immutable.
Please see my complete answer, Solution 1.
—SA

3 solutions

Solution 2

Linq[^] would be helpful in this case.

I would suggest to use Union[^] statement.

C#

string[] filesHD = {"file1.hd","file2.hd"};
string[] filesDT= {"file1.dt"," file2.dt"};
string[] filesTD = {"file1.td","file2.td"};

var allfiles=filesHD.Union(filesDT).Union(filesTD);

foreach(string file in allfiles) 
{
    Console.WriteLine("file: {0}", file);
}

Note: not tested!

Posted 17-Jan-14 13:12pm

Maciej Los

Updated 17-Jan-14 13:20pm

v2

Comments

Sergey Alexandrovich Kryukov 17-Jan-14 21:51pm

Whatever you do with arrays, they are not immutable (only their elements are), so you always create a brand-new array instance each time, which can be quite inefficient if repeat it, as in your example. With what point do you disagree (this message will server as a reminder for you).

And this Union is just a higher level of Copy. Anyway, this is easier to do without the bugs, so my 5. The real solution would be not creating arrays in first place, if creation of arrays of different size will be later needed. Collections should be used instead.

—SA

Maciej Los 18-Jan-14 7:31am

Thank you, Sergey.
By The Way: I have read your answer one more time and i need to admit that i was really tired... +5!

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Sergey Alexandrovich Kryukov · Accepted Answer · 2014-01-16T06:29:00

The main question should be: why putting them all in a single array?
Also, arrays objects are immutable (even though their elements are mutable), which makes them not very suitable for holding variable-length data; for this purpose, you should better use some collection from System.Collections.Generic, like System.Collections.Generic.List<string>:
http://msdn.microsoft.com/en-us/library/System.Collections.Generic%28v=vs.110%29.aspx[^],
http://msdn.microsoft.com/en-us/library/6sh2ey19%28v=vs.110%29.aspx[^].

You can always get an array from the list using the method ToArray, if you need to.

If you still want to create the array immediately from other array(s) (not recommended for most cases), just use Array.Copy:
http://msdn.microsoft.com/en-us/library/system.array.copy%28v=vs.110%29.aspx[^].

—SA

Karthik_Mahalingam · Accepted Answer · 2014-01-17T14:36:00

Try this..

C#

List<string> lstTemp = new List<string>();
           lstTemp.AddRange(filesHD);
           lstTemp.AddRange(filesDT);
           lstTemp.AddRange(filesTD);
           string[] finalArray = lstTemp.ToArray();

note: pls add this namespace using System.Collections.Generic;

Reference:List AddRange[^]